Beep...Beep...Tracking Frogs

Technological breakthroughs have resulted in the development of tiny (.61 g) radio transmitters. Radio collars have long been used to understand the habitat use and movements of larger animals such as elk, bears, and bighorn sheep. Radio telemetry is a relatively new tool for studying frogs.

Since frogs don’t really have necks to hold a collar, the radio transmitters are attached to a “belt” consisting of fine elastic thread strung with green glass beads. The “inventor” of the wood frog radio belt, Dr. Erin Muths, first experimented with the belts on captive frogs in her Fort Collins lab (Dr. Muths is a scientist with the U.S. Geological Survey.) After the experimental collars were put on, the animals were checked frequently for behavior changes, weight loss, or injuries. After Dr. Muths was satisfied that the transmitter assembly (belt, radio transmitter, antenna) was safe she submitted records of her experiment to the USGS Animal Care and Use Committee for review. Such committees provide oversight of animal handling and marking techniques. Rocky Mountain National Park requires this type of independent review before issuing a research permit.

The belts were first deployed on park wood frogs in 2003. Wood frogs are of interest because their park population is disjunct (separated in space) from other populations. They occur in Canada, the eastern U.S., in a limited area in Colorado, and in one small population in Wyoming. While other frogs species have been ravaged by disease and mysterious disappearances, wood frogs seem to be holding their own.

So far, the telemetry study indicates that most wood frogs don’t move around very much, though some young frogs move to a new pond when they first breed. They then appear to take up permanent residence in a home range in and around the new pond. One radio signal was followed a considerable distance (300 yards), but the transmitter was found without the frog and a smug looking raven was perched nearby.